This invention relates to a pipe joint for connecting a flexible tube, having a corrugation on an outer peripheral surface thereof, to another flexible tube or an ordinary tube for flowing a fluid such as gas and water.
One such pipe joint is proposed in U.S. Pat. No. 4,630,850, and has been used. This conventional joint comprises a joint body having an externally-threaded portion formed on an outer peripheral surface thereof at one end portion thereof, a cap nut threadedly fitted on the externally-threaded portion of the joint body, and a sleeve having a corrugated inner peripheral surface for engagement with a corrugated outer peripheral surface of a corrugated tube.
The joint body has an axial tapering bore provided at the one end portion thereof (where the externally-threaded portion is provided) which bore is gently decreasing in diameter progressively toward the other end of the joint body. The joint body also has an axial through bore which is formed in the other end portion thereof, and is smaller in diameter than the tapering bore. A tube receiving wall or shoulder is formed at the boundary between this through bore and the tapering bore.
Axial slits are formed in the sleeve to divide the sleeve into a plurality of segments. The sleeve is fitted on the corrugated tube at a position spaced such a distance from one end of the corrugated tube that several ridges on the outer peripheral surface of the corrugated tube are disposed between the sleeve and the one end of the corrugated tube. Then, the sleeve is inserted into the tapering bore in the joint body, and the cap nut is mounted on the externally-threaded portion of the joint body, and is tightened.
That portion of the corrugated tube projecting from the sleeve is sealed between the end of the sleeve and the tube receiving shoulder of the joint body.
In this pipe joint, a satisfactory seal is formed between the end of the corrugated tube and the tube receiving shoulder of the joint body, and therefore a fluid will not leak from this sealed portion. The sleeve, having the corrugated inner peripheral surface engageable with the corrugated outer peripheral surface of the corrugated tube, is fitted on the outer periphery of the corrugated tube, and this sleeve is fixedly secured to the joint body by the cap nut, and therefore a positive connection of the corrugated tube can be achieved.
However, there may be encountered such an assembling mistake that the end portion of the corrugated tube is completely received within the sleeve, in which case the end portion of the corrugated tube is not projected from the end of the sleeve. Even in this condition, the pipe joint can be assembled, and the cap nut can be tightened. If the pipe joint is thus assembled, the end of the corrugated tube will not be compressed between the end of the sleeve and the tube receiving shoulder of the Joint body, so that a seal is not formed between the end of the corrugated tube and the joint body. This results in leakage of a fluid from this portion.
For connecting the corrugated tube to the above pipe joint, the joint is first disassembled, and the cap nut and the sleeve are fitted on the corrugated tube, and the corrugated tube with the sleeve is inserted into the joint body, and then the cap nut is engaged with the joint body, and is tightened. Several ridges on the end portion of the corrugated tube need to be compressed by tightening the cap nut.
There has been a demand for the type of pipe joint capable of connecting a corrugated tube merely by inserting the corrugated tube thereinto, and various such proposals have been made. However, none of such proposals have proven to be sufficiently reliable in sealing ability. It is possible to insert a corrugated tube into a pipe joint and to mechanically retain the corrugated tube relative to the pipe joint against withdrawal. In such a case, however, since a large pressure is not applied, a satisfactory seal can not be achieved.